The invention relates to a digital clock in which the time of day is continuously displayed. More particularly, it relates to a digital clock capable of receiving input data pertinent to a function to be performed by the clock, which data can be displayed instead of the current time.
A clock of this type is described in commonly assigned German Pat. No. 2,117,756. In the device of this patent, data for the adjustment or shifting of the time displayed by the clock is supplied through a first feeding mechanism. Pertinent dates or deadlines are entered and addressed through a second feeding mechanism, which is designed as a keyboard. In operation, the deadline or date is entered via the keyboard and digitally stored in a deadline memory. After entry has been completed, a function key labelled as an address key is operated and the stored data is displayed by the clock's display mechanism. A comparator within the device continuously compares the current clock time with the stored deadline or date. When the two coincide, display of the current time is interrupted and the deadline or date is displayed along with the production of an acoustic signal. The acoustic signal and the display of the deadline or date is terminated by operation of a second function key, after which the current time is again displayed. The device also includes a circuit which terminates the acoustic signal and the display of the deadline or date automatically if the second function key is not operated within a predetermined time period.
A device of this type possesses certain inherent drawbacks. The requirement of two feeding mechanisms for different functions imposes an unnecessary manufacturing cost. The inability to display the data as it is being entered results in a time consuming process should the need for error correction arise.
Digital clocks with data storage and diverse function operation of the type described have been utilized for the automatic control of an electric range. In one type of prior art device used for this purpose, an operating key is actuated to suppress the display of the current time on the display mechanism of the clock. This provides the operator with a time period of approximately 20 seconds within which input data such as the start of cooking time, the end of cooking time or the duration of cooking can be entered. If all the necessary data has not been entered within the 20 second interval, the process is interrupted and the entry of data operation must be repeated until it can be accurately and completely accomplished. The drawback of such a time constraint on the operator is readily apparent.